These two craters, located in Orientale basin, show a sharp contrast in albedo. Why are they so different? The likely culprit is the material that each crater is excavating. In this northern section of the Orientale basin, the original dark mare surface has been hidden by brighter highlands material. Because the dark halo crater is larger, it excavates material from greater depth. This allowed the dark crater to excavate the darker mare material while the bright crater only excavated highlands shallower material. In fact it appears that this smaller crater may have excavated darker material on its western side. Using relationships such as these, scientists can estimate how thick the highlands material is on the mare!

LROC Wide Angle Camera (WAC) context mosaic showing the location of the NAC frame, above. The Outer Rook Mountains are to the south and the Cordillera Mountains border the mare to the north; field of view = 100 kilometers. View the full-sized WAC context mosaic HERE [NASA/GSFC/Arizona State University].

Further context for the context image above, in a full-scale view of the mountainous inner rings and interior of Mare Orientale, from the LROC Wide Angle Camera mosaic released June 17, 2010 [NASA/GSFC/Arizona State University].